BRAINCAKEDark Matter
Dark matter is matter that does not emit or absorb electromagnetic radiation, so it cannot be seen directly. We know it is there only because of its gravitational effects on visible matter.
The main evidence comes from the rotation curves of spiral galaxies. A rotation curve is a graph of the orbital speed of stars against their distance from the centre of the galaxy.
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More in Astrophysics and Cosmology
- The Cosmological Principle
- The Doppler Effect and Red Shift
- Hubble's Law
- The Big Bang Theory
- Cosmic Microwave Background Radiation
- The Age of the Universe
- Evolution of the Universe
- Dark Energy
All 24 lessons in Astrophysics and Cosmology · All OCR A-level Physics topics